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Invariant solutions of minimal large-scale structures in turbulent channel flow for Reτ up to 1000

Hwang, Yongyun and Willis, Ashley P. and Cossu, Carlo Invariant solutions of minimal large-scale structures in turbulent channel flow for Reτ up to 1000. (2016) Journal of Fluid Mechanics, 802. R1-1-R1-13. ISSN 0022-1120

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Official URL: http://dx.doi.org/10.1017/jfm.2016.470

Abstract

Understanding the origin of large-scale structures in high-Reynolds-number wall turbulence has been a central issue over a number of years. Recently, Rawat et al. (J. Fluid Mech., vol. 782, 2015, pp. 515–540) have computed invariant solutions for the large-scale structures in turbulent Couette flow at Reτ 128 using an overdamped large-eddy simulation with the Smagorinsky model to account for the effect of the surrounding small-scale motions. Here, we extend this approach to Reynolds numbers an order of magnitude higher in turbulent channel flow, towards the regime where the large-scale structures in the form of very-large-scale motions (long streaky motions) and large-scale motions (short vortical structures) emerge energetically. We demonstrate that a set of invariant solutions can be computed from simulations of the self-sustaining large-scale structures in the minimal unit (domain of size Lx = 3.0h streamwise and Lz = 1.5h spanwise) with midplane reflection symmetry at least up to Reτ = 1000. By approximating the surrounding small scales with an artificially elevated Smagorinsky constant, a set of equilibrium states are found, labelled upper- and lower-branch according to their associated drag. It is shown that the upper-branch equilibrium state is a reasonable proxy for the spatial structure and the turbulent statistics of the self-sustaining large-scale structures.

Item Type:Article
Additional Information:Thanks to Cambridge University Press editor. The definitive version is available at http://www.cambridge.org. The original PDF of the article can be found at Journal of Fluid Mechanics website : https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/invariant-solutions-of-minimal-large-scale-structures-in-turbulent-channel-flow-for-reunicodestixx1d70f-up-to-1000/BEC530DD1BDC2DE10EB757277A2BF72C
HAL Id:hal-01392442
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > University of Sheffield (UNITED KINGDOM)
Other partners > Imperial College London (UNITED KINGDOM)
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Deposited On:08 Sep 2016 14:33

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